To study the durability of high-performance concrete against sulfate attack, the durability indicators of concrete under different water cement ratios, Na2SO4 concentrations, different admixtures, and different experimental conditions during a certain age period were measured, and their regularity was analyzed. The test results show that when the water cement ratio of the concrete specimen is not greater than 0.38, there is no significant change in the flexural strength of the specimen, and the sulfate attack test has no damage to the concrete specimen. When the water cement ratio of the specimen is greater than 0.38, the flexural strength of the reference mortar without admixtures decreases. In contrast, the flexural strength of the specimen with admixtures remains unchanged, indicating that adding admixtures is beneficial for the resistance of the mortar to sulfate attack. For the same concrete specimen, the SO3 content at depths of 1 cm and 6 cm decreases with increasing depth, and a law reflecting the rate of sulfate attack is obtained.